Impact of Cross-Sectional Design in Single-File Rotary System on Apical Debris Extrusion

September 2, 2026 updated by: Nahla Nasr El-Din Fouad, Minia University

Impact of Cross-Sectional Design in Single-File Rotary System on Apical Debris Extrusion and Postoperative Pain Following Single-Visit Root Canal Treatment: An In Vitro and Randomized Clinical Study

Endodontic treatment aims to achieve optimal biological outcomes while minimizing patient's discomfort during and after the procedure. Postoperative pain remains a common complication and is considered a multifactorial phenomenon influenced by several factors, including preoperative pain, age, gender, systemic health, presence of apical periodontitis, instrumentation technique, type and design of endodontic instruments, and the use of intracanal medications.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Root canal shaping represents a critical phase in endodontic treatment, as it facilitates effective cleaning and disinfection while preserving the original canal anatomy. The objective is to create a continuously tapered conical shape from coronal to apical regions without inducing procedural errors such as canal transportation, ledge formation, zipping, or perforation.

With advancements in nickel-titanium (NiTi) technology, modern rotary systems have been developed to enhance shaping efficiency, improve debris removal, and reduce preparation time. Recently, single-file rotary systems have gained popularity due to their simplified protocols, reduced instrument fatigue, and improved clinical efficiency.

A novel concept in instrument design involves flat-sided rotary files manufactured from proprietary heat-treated NiTi alloys, such as AF One Blue and Platinum V.EU. These instruments exhibit a modified S-shaped cross-section with an inactive tip and a distinctive flat surface. The flat-sided design reduces the metal mass of the instrument, potentially enhancing flexibility, cyclic fatigue resistance,and facilitating coronal transportation of debris during instrumentation.

In contrast, One Curve is a single-file rotary system manufactured from heat treated C-wire alloy, which offers controlled memory properties, improved flexibility, and enhanced resistance to cyclic fatigue. It operates in continuous rotation and features a variable cross-sectional design that promotes efficient cutting while maintaining effective debris removal during canal preparation.

Apical extrusion of debris is an inevitable consequence of root canal instrumentation. The extrusion of dentinal debris, microorganisms, and irrigants beyond the apical foramen may induce an inflammatory response in the periapical tissues, which is considered a major contributing factor to postoperative pain. The amount of apically extruded debris has been shown to vary according to the design and kinematics of the instrumentation system used.

Despite the continuous evolution in instrument design, there is limited evidence regarding the influence of flat-sided rotary systems compared to non-flat cross-sectional systems on apical debris extrusion and postoperative pain,particularly in curved canals. Furthermore, the potential relationship between debris extrusion and the severity of postoperative pain remains insufficiently explored.

Study Type

Interventional

Enrollment (Estimated)

30

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • Egypt
    • Minya Governorate
      • Minya, Minya Governorate, Egypt
        • Recruiting
        • Endodontics, Faculty of Dentistry, Minia University
        • Contact:
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Teeth with mature apex
  • Straight root canal or mild curvature not exceeding(5-10) Schneider.
  • Has intact crown ( coronal structure)
  • Presence of one orifices and one apices, patency achieved by a #10-15 K-file to the apical foramen

Exclusion Criteria:

  • Previous root canal treatment.
  • Internal/external resorption.
  • Immature root apices.
  • Caries/cracks/fractures on the root surface.
  • Root canal curvature more than 10 degrees.
  • Teeth in which the apical minor constriction was gauged larger than a size 20 hand file.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: one curve file
About 15 cases will be subjected to one single file to the full working length. File will be operated at 300 rpm/2.5 Ncm torque in continuous rotation
Procedure: AF One single-file rotary system
to evaluate and compare the amount of apically extruded debris using the AF One single-file rotary system, featuring a flat-sided design, and the One Curve rotary system in curved mesiobuccal canals of mandibular first molars. Additionally, this study aims to assess postoperative pain associated with both systems and to investigate the potential correlation between apical debris extrusion and postoperative pain.
Other Names:
  • One Curve rotary system
Active Comparator: AF Fanta flat sided file system
About 15 cases will be subjected to one single file to the full working length.File will be operated at 300 rpm/2.5 Ncm torque in continuous rotation
Procedure: AF One single-file rotary system
to evaluate and compare the amount of apically extruded debris using the AF One single-file rotary system, featuring a flat-sided design, and the One Curve rotary system in curved mesiobuccal canals of mandibular first molars. Additionally, this study aims to assess postoperative pain associated with both systems and to investigate the potential correlation between apical debris extrusion and postoperative pain.
Other Names:
  • One Curve rotary system

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Treatment of Postoperative Pain
Time Frame: from 0 hours to 1 week after the procedure
Pain scores will be recorded on Visual Analog Scale (VAS) using a 0 to 10 pain score basis with 0 being no pain and 10 being the worst pain. Recording will be done everyday for 7 days period.
from 0 hours to 1 week after the procedure

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Minia University

Investigators

  • Study Chair: Maged Mohamed Negm, Professor, Endodontics Department, Faculty of Dentistry, Cairo University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

June 1, 2026

Primary Completion (Estimated)

December 20, 2026

Study Completion (Estimated)

December 30, 2026

Study Registration Dates

First Submitted

September 2, 2026

First Submitted That Met QC Criteria

September 2, 2026

First Posted (Actual)

September 9, 2026

Study Record Updates

Last Update Posted (Actual)

September 9, 2026

Last Update Submitted That Met QC Criteria

September 2, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • Single-File Rotary System

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Subscribe